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Full text of "The manufacture and properties of iron and steel"

oxygen is .furnished by the limestone. I find also a close agreement in the records published by Mr. Talbot. The six heats given by him are not consecutive, but the composition of the metal before the first addition of pig-iron and after the last addition were similar, as shown by the following averages:
C.               P.            Mn.
First metal...................06              .030             .10
Last metal....................13              .035             .15
It would seem fair, therefore, to add together the amounts of pig-iron and ore for the six heats, and to average the figures showing the chemical composition. The results are given in Table XII-H, all estimated figures being in parentheses:
TABLE XII-H. Oxygen used in the Talbot Furnace.
Total pig iron In six heats.................... 212,100 pounds.
j 0    3.75      P 0.85 .............") MnO.60     Si 0.58
Average composition.
Additions.	Pounds.	Per rent, metallic iron.	Pounds free oxygen.
Scale ..... . . ...	22 400	74 5	4768
Ore ..............	15,100	68.0	3754
	13800	66.8	2634
Manganese ore. .. Limestone ...... .	2.500 23,240	(20.0)	620 2,70^
Total .......			14476
The ore and limestone account for 14,476 pounds of oxygen. This assumes that the carbonic acid of the limestone is broken up when in contact with melted pig-iron and that one atom of oxygen is set free. The amount of silica present is shown in Table XII-I. The average of the slags showed 12.75 per cent. Si02 and 15.13 per cent. Fe=19.45 per cent. FeO. According to this proportion, the presence of 4827 pounds of Si02 in the slag would call for 7364 pounds FeO=5728 pounds Fe, and 1636 pounds of oxygen would be held  by this iron and not be available for oxidizing the metalloids. The calculation, therefore, shows that 14,4761636=12,840 pounds of oxygen are available. The amount of oxygen required is shown in Table XII-J: